The central nervous system (CNS) acquires its vasculature by angiogenesis, a process consisting of proliferation of endothelial cells in existing blood vessels or vascular plexuses, and leading to the formation of new blood vessels. Notions of cerebral vascularization often depict CNS angiogenesis as a passive process driven primarily by demands of oxygen and to meet the metabolic needs of growing neuronal populations. They treat the developing endothelial network as a homogenous population. Our work has challenged these notions and shown that telencephalic blood vessels fall into two categories: pial and periventricular, based on anatomical location, independent growth patterns and developmental regulation. The neural tube acting as a vessel patterning nexus, directs the formation of the pial vessels that encompass it. The pial vessels do not display developmental gradients and are present circumscribing the entire telencephalon by embryonic day 9 (E9). The periventricular vessels on the other hand are branches of a basal vessel located in the basal ganglia primordium that likely arises from the pharyngeal arch arteries in the cervical region by E9. The periventricular vessel network propagates in an orderly lattice pattern into the dorsal telencephalon by E11 regulated by homeobox transcription factors. This application will test the central hypothesis that periventricular endothelial cells provide critical cues for the establishment of later forming neuronal gradients in the embryonic telencephalon. It aims at highlighting the autonomy of periventricular endothelial cell development and how it is regulated independently of neuronal development. It explores the novel concept that periventricular endothelial cells have an agenda of their own with remarkable versatility in being able to sculpt neuronal networks. It attempts to tap into the tremendous potential of periventricular endothelial cells as a therapeutic source for recovery of neurological function in many diverse scenarios. Results will have far-reaching effects on concepts and mechanisms of regulation of angiogenesis, offer new perspectives on telencephalic histogenesis principles and will lead to discoveries with unprecedented implication for treatment of many neurological disorders. PUBLIC HEALTH RELEVANCE: This research is relevant to public health because it will offer novel insights into CNS angiogenesis that will permit us to develop effective and new therapies to promote repair of brain damage in many diverse scenarios.